The present invention relates to an information recording medium which has a header field where header data is emboss-recorded in advance, and a recording field where recording data is phase-change-recorded. The present invention also relates to an information reproduction apparatus which binarizes a reproduced signal that reflects data recorded on an information recording medium by a predetermined slice level, and reproduces data recorded on the information recording medium on the basis of the binary reproduced signal.
In recent years, as large-capacity information recording media, optical disks such as a DVD (Digital Video Disk)-RAM (random access memory) and the like have been extensively studied. A DVD-RAM disk assures a large capacity by high-density recording. The DVD-RAM disk alternately has land and groove tracks in a spiral pattern, and data can be recorded on both the tracks.
The DVD-RAM disk has a header data area between the neighboring tracks, and also has a recording data field in the tracks. On the header data area, header data modulated by 8-16 modulation is emboss-recorded in advance (before delivery). Recording and reproduction to and from the recording field are done in accordance with the header data. User data modulated by 8-16 modulation is phase-change-recorded on the recording field.
A reproduction apparatus for reproducing a DVD-RAM disk binarizes a reproduced signal that reflects data recorded on the DVD-RAM disk by a predetermined slice level, and reproduces data based on the binary reproduced signal.
However, on the DVD-RAM disk, neighboring recorded data (neighboring header data) become too close to each other because of high-density recording. When the neighboring header data are too close to reproduce normally, recording and reproduction on the recording field are disabled.
Since 8-16 modulation is used, a cutting device for emboss-recording header data on the DVD-RAM disk is complicated.
Furthermore, the reproduction apparatus cannot always assure an appropriate slice level signal, and when the appropriate slice level signal cannot be assured, reproduction precision deteriorates.